There are two important causes of mural deterioration.One is the salt migration and enrichment caused by water movement,and the other is the soil stress change caused by soil-water interaction.Both are related to the soil-water characteristics.This paper describes the research on the soil-water characteristics of the soil in mural plaster by laboratory tests,intending to provide theoretical guidance for mural conservation.By using pressure plate extractors,the soil-water characteristic curve(SWCC) of washed soil(dengbantu),which is the plaster material in the Mogao Grottoes murals,was measured.The relationship between matrix suction and water content was analyzed,and the curve morphology and model for SWCC of washed soil were also studied.The saturated hydraulic conductivity of washed soil was tested by flexible-wall permeameter,and then the unsaturated hydraulic conductivity in different water content was calculated through the Van Genuchten(1980) prediction model.Based on the measurement and calculation,the correlation between unsaturated hydraulic conductivity and water content(matrix suction) was established.Research results show that the unsaturated hydraulic conductivity of washed soil decreases non-linearly as the water content decreases,while at a high-suction section(100-100000kPa) it has a linear decline at a certain specific rate as the matrix suction increases in double logarithmic coordinates.
